This is a clever way to do this. I just fix my hot water problem. The problem is on electrovalve. It is blocked by scale. After I break apart and clean it, it work well.But before I doing that, I made a big stupid mistake. I use multimeter to check the voltage and "current". When I check the voltage, I found there is no problem with switching on and off. However I want to make sure, I detect the current. Then I saw a spark on the circuit board. The fuse burned. I replace a new one, But I can not switch off any more. It is turn on all the time......

I still want to fix the circuit board, but there is no sign of burn like yours. I think the easy way is to add a momentary switch like what you did.

In a home environment, I think the La Marzocco switch works as well if not better than the original "dose at a time". Momentary is the wrong word; you just hold it down for water and it springs to the closed position when released.

Yes! He lowered the price to 150$ and I got it for 125$. Not sure if that's an amazing price, but I went for it regardless. It's missing it's drip tray cover and the side and top-back panels. So I have to fashion my own.

I want to rewire it, but I don't know where to get the silicon wire. I need the new knob and it's even missing filter baskets and other stuff.

Those are octocouplers, they disconnect the two electrical circuits (AC/DC in this case). You should be able to replace them quite cheaply as well. They are used to monitor the switches and buttons and I believe to trigger the electro-switches that at least some of the S20s use.

Are yours soldered directly to the board? I'm doing a restoration of a S27 but I haven't gotten that far yet.

EDIT: just took a look at a photo of the board that I have. Everything is indeed soldered to the board. Pretty crazy looking thing. Z80 processor, sheesh. I bet this thing could be shrunk down nowadays.

You guys are too good. I don't even know what those gadget are. I just surf on a website for repairing espresso. According to what they say, this is a common problem for S27. If the wire of hot water switch is good, then the problem might be optocouplers and power transistors.

There is no problem to install, but the hardest part is too remove it, especially for power transistors. The legs of the transistor is too fit. I have to clean all the solder of course and use a lot of force to remove it while heating it. Fortunately, they are too strong to break it, even too hot to hold it (I wonder why does it can be broken by current but not broken by heat up to 70C or more).

Anyway, Steven, I know your machine is good enough. The program of hot water is useless for home user. I just want to play with it. Maybe this is a start for writing an app.

I got my circuit board out, wondering what people know about this blue thing. What is that? I believe it's some sort of jumper. There are two on the board, this particular one is near the top left and it is disconnected. How does everyone elses look like?

I believe that one is for the "economizer" circuit on some S20 models. If open it has the pump run when the hot water function is activated. Economizer valve mixes pumped cold and hot boiler water to control the hot water temperature.

The other jumper disables programming of dose buttons. That's near the upper right.

Oh very cool. I was taking the wiring harness out of my s27 and I didn't really understand what that fork in the piping from the pump was for! These things are really complicated with the number of electro valves etc. In some ways this machine does the same thing as a Silvia, but they're 100 times more complicated considering that Silvia has pretty much nothing going on inside of it. It's really fascinating how efficient the consumer models are.

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